1. Technical Field
The field relates to sound generation and projection and more particularly to a toroidal whistle assembly for generation and projection of a high intensity sound beam.
2. Description of the Technical Field
Toroidal whistles have a cylindrical blade aligned on an annular gas outlet/orifice of the same diameter. A jet of air from the outlet impinges on the blade, which is spaced from the orifice to define the whistle mouth. The flow of the jet alternates from side to side of the blade in response to pressure changes in a resonance chamber located to the inside of the blade. The diameter of the torus shaped resonance chamber adjacent the blade can be increased without altering the cross sectional area of the resonance chamber by adjusting the size of an interior cylinder. This allows construction of whistles of very large diameters without change of the whistle resonant frequency. Toroidal whistles thus can be expanded to operate at extreme volume levels while retaining virtually any desired design frequency. Locomotive whistles are a well known example of an application of toroidal whistles. A modern toroidal whistle is taught in U.S. Pat. No. 4,429,656 to Weisenberger.
Weisenberger adapted his whistle design to construct a directional toroidal whistle as taught in U.S. Pat. No. 4,686,928. There a toroidal whistle was inverted (the annular mouth of the whistle was placed to face inwardly) and the annular mouth was located near the base of a horn. A phase plug was centered at the horn base surrounded by the annular whistle mouth.